Production of thorium-uranium alloys



This invention relates to a method of producing thorium-uranium alloys.

The object of the invention is to provide a convenient and economical method of incorporating uranium, U or U and particularly the former, in thorium with high, reproducible recovery.

In carrying out the process of the invention uranium tetrafluoride, UF is mixed with thorium metal particles and the mixture heated to form a thorium-uranium alloy phase and a thorium-fluoride phase or slag which are readily separated from each other. While the process may be carried out under vacuum conditions, it is preferable to employ an inert atmosphere, such as one atmosphere of argon to insure avoidance of oxidation and to suppress distillation of volatile halide during the reaction. This insures higher alloy recovery and the results are readily reproducible. In vacuum the reaction begins at about 650 C. and under one atmosphere of an inert gas at about 1000 C. Due to the exothermic nature of the reaction the temperature rises to 1200-1400" C. and the heating is continued to a temperature of at least 1600 C. to insure clean separation of the alloy and slag. An excess of thorium particles is preferably used, depending upon the desired proportion of thorium in the thorium-uranium alloy to be produced.

The following examples illustrate the operation of the process:

(l) 80 g. of uranium tetrafluoride, UF and 100 g. of thorium metal turnings were mixed intimately and were placed in a graphite crucible. The graphite crucible containing the reactants was then heated in a quartz tube induction furnace under an argon atmosphere. The temperature reached 1000" C.: after thirty minutes of heating, at which point the exothermic reaction between the reactants took place raising the temperature rapidly to 1200-1400 C. The heating was continued until the temperature reached 1650" C. The furnace was then cooled.

Patented June 6, 1961 The products separated into two layers-11 bottom layer of Th-U alloy weighing 93 grams and a top slag layer weighing 72 grams. The layers separated cleanly at the interface upon cooling. This represents a recovery of 90.6% of the uranium and 93% of the thorium in the alloy billet. The slag contained 0.9 gram uranium and the rest appeared as a carbide layer and in fluoride absorbed on the walls of the crucible, and was readily recoverable by normal wet chemical techniques.

(2) To produce a more dilute uranium alloy 180 grams of thorium were mixed with grams of UF The mixture was pressed into pellets under a pressure of 8000 psi. These were heated as in Example 1. The reaction initiated at 1000 C. and heating was continued to 1650 C. The alloy and slag were easily and cleanly separated upon cooling.

The alloy billet contained 32% U giving a 91.2% uranium recovery in the alloy. 1% of the uranium appeared in the slag and the balance in the furnace crucible as before. The thorium recovery in the alloy was 98%.

The slag layer protects the alloy from oxidation and reaction with the crucible. The process is particularly useful in the preparation of thorium alloys containing U where the overall yield of uranium is important.

What is claimed is:

1. A process of producing thorium-uranium alloys which comprises mixing thorium metal particles with uranium tetrafiuoride in an amount suflicient to reduce the uranium tetrafluoride with formation of thorium tetrafluoride and to form the desired alloy, heating the mixture in a graphite crucible to initiate reaction between the thorium and uranium tetrafluoride, continuing the heating to a temperature of at least 1600" C. to form an alloy phase and a slag phase, cooling the reaction products and separating the slag from the alloy.

2. The process defined in claim 1 wherein the mixture is heated in an atmosphere of inert gas.

3. The process defined in claim 1 wherein the mixture is heated to a temperature not substantially less than 1650 C. in an atmosphere of argon.

References Cited in the file of this patent UNITED STATES PATENTS 1,648,954 Marden Nov. 15, 1927 2,678,267 Saunders May 11, 1954 2,875,041 Runnalls Feb. 24, 1959 

1. A PROCESS OF PRODUCING THORIUM-URANIUM ALLOYS WHICH COMPRISES MIXING THORIUM METAL PARTICLES WITH URANIUM TETRAFLUORIDE IN AN AMOUNT SUFFICIENT TO REDUCE THE URANIUM TETRAFLUORIDE WITH FORMATION OF THORIUM TETRAFLUORIDE AND TO FORM THE DESIRED ALLOYD, HEATING THE MIXTURE IN A GRAPHITE CRUCIBLE TO INITIATE REACTION BETWEEN THE THORIUM AND URANIUM TETRAFLUORIDE, CONTINUING THE HEATING TO A TEMPERATURE OF AT LEAST 1600* C. TO FORM AN ALLOY PHASE AND A SLAG PHASE, COOLING THE REACTION PRODUCTS AND SEPARATING THE SLAG FROM THE ALLOY. 